For those who haven't updated to PS3 Firmware 2.50 yet, here are the translated details courtesy of PSPImages.net:
The emulator has been programmed in BD-J code, a form of JAVA, which is normally used for advanced Blu-ray menus. The emulator is a bit slow and there is not much sound but it's easy and works very well.
1. Download the emulator
2. Place the AVCHD on an USB drive (use FAT32)
3. Place the drive in the USB port of the PS3
4. Select the drive and start the AVCHD folder from VIDEO
5. Choose a game
You can use the triangle button to select the numbers...
Roughly translated, tmaster has concluded the following:
"FW2.50 not start in the BD-J.
Upgrade to stop so we can update orz"
I don't know if Bu-nyan is saying its ok to upgrade or not.
Update: I can confirm that bd-j don't work with 2.50. I tried it on my brothers ps3 and it gives me an error. good thing I still have mine at 2.43 to play java.
Why sony stopped I don't know.. maybe a hack, who knows?
Note: FYI, although most of the PS3 Devs are sleeping CJPC said the following on IRC: "It probably is on, but they may have changed it a bit.. possibly to only work from a pressed bd-rom or some bs, which, still makes 0 sense. bd-j functionality is CORE for any bd player.. at profile 2.0 that the ps3 has (or 1.1, can't recall) so bd-j is not off, something just changed with it."
That being said, it may explain why Bu-nyan and others are reporting BD-J as not working... when...